The present invention relates to a seat device of a vehicle which is preferable for a seat for a driver.
The seat device of the vehicle includes a seat comprising a seat cushion and a seatback which is connected to a rear end portion of the seat cushion so as to swing longitudinally. In the seat device for the driver's seat, in particular, it is required to provide an appropriate driving position for a pedal operation and also ensure fine front visibility regardless of the body size. Accordingly, a lift mechanism for adjusting the height of the seat as a whole is also provided additionally to a seatback swing-angle adjusting mechanism and a seat longitudinal-position adjusting mechanism (slide adjusting mechanism). Japanese Patent Laid-Open Publication No. 2009-96423 proposes a device in which a thigh support portion is provided at a front end portion of the seat cushion. Herein, the thigh support portion is configured to swing (rotate) vertically around its rear portion such that a swing angle of the thigh support portion is adjustable, whereby a passenger's thigh portion can be properly supported by the thigh support portion.
Further, the longitudinal-position adjustable seat is generally provided to slide with a front-upward slant angle (by a slide rail having the front-upward slant angle) such that the height of the seat located at a forward position is slightly greater than that of the seat located a rearward position.
Herein, it is required as the appropriate driving position that a comfortable state can be maintained (a situation where a muscle does not need to produce any particular force during a normal driving state) and also an operational force for pedal operation can be generated sufficiently when needed. More specifically, it is required from a pedal-operation perspective that plural joint angles (such as a hip angle, a knee angle, and an ankle angle) at a lower part of a body below a waist can be within a specified angle range and also, in particular, the thigh portion can be supported properly. Further, it is required in order to ensure (provide) the fine front visibility that a shortest clear-vision distance (the shortest distance from a longitudinal position of eyes of a passenger to a point on a road surface which is visible to the passenger through a windshield) is not too great or not too small.
In the meantime, it may be considered from view points of light weight and the like that the vehicle is not equipped with the above-described lift mechanism (the mechanism to move vertically the seat as a whole) which is large-sized and heavy. In this case, it becomes difficult to compatibly achieve ensuring of the appropriate driving position and ensuring of a proper driving visual field for all passengers from a preset small body-sized passenger and a preset large body-sized passenger.
Herein, in a conventional device, the above-described front-upward slant angle of the longitudinal position adjustment is generally set at 6 degrees or smaller, so that the move (change) amount of the height of the seat is so small that it is difficult to even ensure the fine front visibility for all passengers from the small body-sized passenger to the large body-sized passenger.